In this study published in Health Affairs this month, researchers investigated the concept known as “additionality,” where donor nations and philanthropic organizations “require that funds provided for a specific health priority such as HIV should supplement domestic spending on that priority.” Using data from Honduras, Rwanda, and Thailand, the authors found that “the three countries increased funding for HIV in response to increased donor funding” and “suggest that it would be preferable for donors and countries to agree on how best to use available domestic and external funds to improve population health, and to develop better means of tracking outcomes, than to try to develop more sophisticated methods to track additionality” (February 2012).